ihatemybike
Explorer
It's a sad day. Another Astro is removed from the road, most likely never to be driven again.
Good info in the postmortem.
Good info in the postmortem.
Newbie AWD Astro Overlander Build
- Thread starter nobodyhome
- Start date
villageidiot327
Explorer
So, whatdya do with the van? Knock sensor, o2, and misfire, maybe it lost the timing gears, maybe the distributor drive gear on the distributor.
I get being frustrated, but really, you're probably pretty close to having it figured out.
I get being frustrated, but really, you're probably pretty close to having it figured out.
Sorry to see it go. Any idea what you're looking for next?
I empathize with you. I fear I too am currently just flushing a large chunk of cash down the toilet with my Astro who died return from a ski trip in WY. Thus far I'm out about $600 with fuel pump replacement and tows...but it sounds horrible when driving -- airy on acceleration. Probably a bad intake manifold gasket but who knows....Hopefully limping it home 50mi from my friend's didn't kill the thing.
I empathize with you. I fear I too am currently just flushing a large chunk of cash down the toilet with my Astro who died return from a ski trip in WY. Thus far I'm out about $600 with fuel pump replacement and tows...but it sounds horrible when driving -- airy on acceleration. Probably a bad intake manifold gasket but who knows....Hopefully limping it home 50mi from my friend's didn't kill the thing.
86cj
Explorer
intake gasket
I know you made your decision and have been in your shoes, I also know fixing it after such a battle fells pretty good, no really good.
The intake gasket needs changed on those motors just like a normal wear item. I have fought almost all the issues on a 2000 4.3, also did the spyder upgrade mine cracked and dumped fuel down one side of the motor. I cured my long long battle with random mis-fire with a "new dist" and ac delco coil wires and cap, MSD ignition upgrade gave me tons on random mis-fire issues when damp and cold within 6 months of install. The local parts guy told me to use only ac delco ignition parts, he was right lesson learned.
You are so close with all the new stuff I hate to see another 4.3 pushed aside due to a intake gasket, the gasket is cheap the labor is not to bad compared to all your effort to date. If you change your mind and do the intake gasket, (flushing the oil pan really well is key) alot of people lose the bearings a week after the intake change due to anifreeze or debris in the oil. Taking a vehicle into the back country that you understand how it functions is a great thing, I would say you are there if it dies you now have some idea what it might be.
BTW: my MPG's after the spyder change are worse, but it burns no oil and has great oil pressure it has over 160,000 miles with the last 50,000 trouble free.
I know you made your decision and have been in your shoes, I also know fixing it after such a battle fells pretty good, no really good.
The intake gasket needs changed on those motors just like a normal wear item. I have fought almost all the issues on a 2000 4.3, also did the spyder upgrade mine cracked and dumped fuel down one side of the motor. I cured my long long battle with random mis-fire with a "new dist" and ac delco coil wires and cap, MSD ignition upgrade gave me tons on random mis-fire issues when damp and cold within 6 months of install. The local parts guy told me to use only ac delco ignition parts, he was right lesson learned.
You are so close with all the new stuff I hate to see another 4.3 pushed aside due to a intake gasket, the gasket is cheap the labor is not to bad compared to all your effort to date. If you change your mind and do the intake gasket, (flushing the oil pan really well is key) alot of people lose the bearings a week after the intake change due to anifreeze or debris in the oil. Taking a vehicle into the back country that you understand how it functions is a great thing, I would say you are there if it dies you now have some idea what it might be.
BTW: my MPG's after the spyder change are worse, but it burns no oil and has great oil pressure it has over 160,000 miles with the last 50,000 trouble free.
To be clear my post about my likely intake gaskets woes is not the same as the OPs troubles which seem much harder to isolate.
The intake gaskets parts are cheap, but the labor is damn expensive. I know DIY is the answer here, but I've got a) no experience working on engines b) no garage c) no place I can leave a non-functioning vehicle while I work on it and d) no other vehicle to get to the mountains. So its have a shop do it, or sell/junk it now.
nobodyhome
Adventurer
DOCTOR, WE HAVE SOMETHING! It's faint, but might be hopeful!
Just got off the phone with my local stealership, whom I will now refer to as just Dealership. The service rep I talked to was very familiar with this motor. He gave me one of the best leads i've gotten so far, so I'm going to share it with you all.
4.2L V6
- The valve guides on this motor were made with a abnormally tight tolerance; .001" as opposed to the more common .0015". This reduced clearance makes them more susceptible to sticking open, ESPECIALLY when the motor heats up.
Conclusion: Consistent with current issues
- Cyl #5 is the hottest of them all ( 5 & 7 on the V8 version)
Conclusion: Consistent with current issues
PENDING TEST:
- Get engine to full operating temperature
- Put engine under high load, i.e. trans in DRIVE, brake on, low speed, push ~1800 RPM for a few minutes
- If PCM throws P0305 or other misfire, then condition is confirmed
- If PCM throws multiple codes other than misfire, condition is suspected
Possible Temporary Solutions:
* Flush motor with Seafoam or similar engine flush. This may reduce the offending buildup enough to promote normal operation.
* Perform redneck guide ream:
1) Inject and hold cylinder with 150psi to hold valves in place
2) Remove rocker and springs
3) Put drill on valve stem and spin the crap out of it with carb spray in the guide
4) Replace stem seal and reassemble
5) Flush motor, change oil
Permanent Solution:
- Valve job
- Note: My area has a cylinder head exchange who will swap your usable core for a rebuilt head. My local shop charges $150 each. With my limited driveway mechanic skills and FSM, I might be able to get it done myself.
WE just might bring this thing back to life after all!
ihatemybike
Explorer
Interesting. I haven't heard of this issue with the valve guide before, but I like what I hear. Grumpy has a history of P0302, cylinder 2 misfire, that none of the normal fixes resolved. I'll have to try this on it when I fire it back up.
Mwilliamshs
Explorer
Sticking valve guides is fairly common on the 4.3 but it's really a case of cause and effect more so than just a tight tolerance on valve guides.
Cause A: Leaky intake manifold gasket causes lean condition leading to partial burn (aka misfire) in cylinder causing excess build-up on valve stem.
Effect: Valve sticks in guide, hanging open, loss of compression, misfire
Cause B: Faulty injection spider/injector/fuel pump/filter causes misfire in cylinder causing excess build-up on valve stem.
Effect: Valve sticks in guide, hanging open, loss of compression, misfire
Cause C: Faulty ignition (plastic distributor, coil failing when hot, etc) causes misfire in cylinder causing excess build-up on valve stem.
Effect: Valve sticks in guide, hanging open, loss of compression, misfire
Cause D-Z:...causes misfire in cylinder causing excess build-up on valve stem.
Effect: Valve sticks in guide, hanging open, loss of compression, misfire
Cause A: Leaky intake manifold gasket causes lean condition leading to partial burn (aka misfire) in cylinder causing excess build-up on valve stem.
Effect: Valve sticks in guide, hanging open, loss of compression, misfire
Cause B: Faulty injection spider/injector/fuel pump/filter causes misfire in cylinder causing excess build-up on valve stem.
Effect: Valve sticks in guide, hanging open, loss of compression, misfire
Cause C: Faulty ignition (plastic distributor, coil failing when hot, etc) causes misfire in cylinder causing excess build-up on valve stem.
Effect: Valve sticks in guide, hanging open, loss of compression, misfire
Cause D-Z:...causes misfire in cylinder causing excess build-up on valve stem.
Effect: Valve sticks in guide, hanging open, loss of compression, misfire
tequilasunset
Adventurer
Happy to hear you have not given up... failure is a bruise not a tattoo
nobodyhome
Adventurer
AWESOME, thanks everyone.
Aaron, Tequila- thanks for the words of encouragement!
Mwilliamshs- Couldn't agree more; it is an effect, not cause, but it was suggested that the tight tolerance makes it a more common occurrence. Cyl 5 injector was initially found leaking, probably for some time, which is why we replaced the spider. That and the motor has 215K miles and the previous owner didn't love it like they should have. Even now the plugs have black gunk on the insulator.
I dumped in an entire bottle of Seafoam (S/B 5oz, used 16oz) in at lunch and ran at 0 load, 1200 RPM for 10 mins. It may be wishful thinking, but I think its getting better. I will run 100 miles under low load, change oil, administer the engine nuke cleaner, change again, then keep my fingers crossed...
JOHNNY! Start I.V., WD40
lubricated ringers, 5mL push
Charge to 300...
CLEAR!
Aaron, Tequila- thanks for the words of encouragement!
Mwilliamshs- Couldn't agree more; it is an effect, not cause, but it was suggested that the tight tolerance makes it a more common occurrence. Cyl 5 injector was initially found leaking, probably for some time, which is why we replaced the spider. That and the motor has 215K miles and the previous owner didn't love it like they should have. Even now the plugs have black gunk on the insulator.
I dumped in an entire bottle of Seafoam (S/B 5oz, used 16oz) in at lunch and ran at 0 load, 1200 RPM for 10 mins. It may be wishful thinking, but I think its getting better. I will run 100 miles under low load, change oil, administer the engine nuke cleaner, change again, then keep my fingers crossed...
JOHNNY! Start I.V., WD40
lubricated ringers, 5mL push
Charge to 300...
CLEAR!
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Mwilliamshs
Explorer
Dumped an entire bottle of Seafoam in at lunch...
In where? To clean a sticking valve stem it'd be best to add it to the intake stream. It would require a leaking valve stem seal for Seafoam added to the crankcase to reach the valve stem/guide and you've given no indication that's the case. Added to the gas tank Seafoam could help prevent deposits but because of the location of your injectors (not TBI afterall) it'd still be best to administer through a vacuum line or directly into the plenum for your purpose of cleaning an already cruddy valve stem.
In where? To clean a sticking valve stem it'd be best to add it to the intake stream. It would require a leaking valve stem seal for Seafoam added to the crankcase to reach the valve stem/guide and you've given no indication that's the case. Added to the gas tank Seafoam could help prevent deposits but because of the location of your injectors (not TBI afterall) it'd still be best to administer through a vacuum line or directly into the plenum for your purpose of cleaning an already cruddy valve stem.
nobodyhome
Adventurer
Crap... wrong end... hate it when that happens... I'm such a NOOOB!
I see, OK thank you. I found a few methods for my Astro, looks like most popular is to slow feed Seafoam directly into the TB / rev the motor a bit then dump an ounce or 2 and let it stall out. Then let it sit overnight and enjoy the morning smoke show! As far as I can tell, this is identical to the Marvel Mystery Oil down the carb trick to free a stuck lifter. Also sounds like filling the fuel filter with Techron trick... Did I get that right?
Thanks!
I see, OK thank you. I found a few methods for my Astro, looks like most popular is to slow feed Seafoam directly into the TB / rev the motor a bit then dump an ounce or 2 and let it stall out. Then let it sit overnight and enjoy the morning smoke show! As far as I can tell, this is identical to the Marvel Mystery Oil down the carb trick to free a stuck lifter. Also sounds like filling the fuel filter with Techron trick... Did I get that right?
Thanks!
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86cj
Explorer
If you are still going forward the intake gasket is pretty much a must do, you will get a good look at the valves to see just how bad they are. My spyder cracked and dumped fuel into one side of intake, it cleaned those valves and plentum the other side looked like an old engine should. Your sticking valve sounds possible and cleaner in the intake can't hurt at this point, keep in mind as that stuff breaks loose it could get on sparkplug and cause a "Random Misfire".....The EGR valve has a history of sticking due to build up, I put a restrictor (a solid EGR gasket with a small hole) and have had no issue since, I don't doubt the valves are very dirty.
If you have to pay labor an intake job does cost around $750, but the gasket kit is an upgrade gasket and cost around $60 if I remember. You are lucky because the cracked plastic gasket normaly dumps anti freeze into the oil and spins the bearings, mine weeped Out of the engine luckily during cool down only. It did not leak warm and running and hardly used any coolant, I think it is about the only reason a 5.7 or 4.3 blows up, some other GM engines had the intake issue to. Again flush the oil pan good after any intake work, alot of engines seize right after you get done fixing them, you will feel very inferior if you do it yourself for $60 and it lasts one day.....If you pay to have it done Browbeating your mechanic about issue is advised...
If you have to pay labor an intake job does cost around $750, but the gasket kit is an upgrade gasket and cost around $60 if I remember. You are lucky because the cracked plastic gasket normaly dumps anti freeze into the oil and spins the bearings, mine weeped Out of the engine luckily during cool down only. It did not leak warm and running and hardly used any coolant, I think it is about the only reason a 5.7 or 4.3 blows up, some other GM engines had the intake issue to. Again flush the oil pan good after any intake work, alot of engines seize right after you get done fixing them, you will feel very inferior if you do it yourself for $60 and it lasts one day.....If you pay to have it done Browbeating your mechanic about issue is advised...
nobodyhome
Adventurer
WE HAVE SINUS RHYTHM!
- Seafoam in crankcase certainly cleaned things up, however, as pointed out by our friend Mwilliamshs above... wrong end. I also did a round of BG's Engine Performance Restorer on fresh oil for giggles and well I think the Seafoam got the bulk of it.
- Added 32oz Seafoam to ~12 gals of gas (x3 recommended dilution) and ran 60 miles under normal load; NOTICEABLE IMPROVEMENT! Instead of barely running and shaking violently, it just shakes now. Although far from the finish line, I believe we have isolated the issue because now we can turn it off and on.
- Full Seafoam trick coming this weekend.
I was surprised to find that a $7 can of Seafoam improved my exponentially declining issue. Can't wait to see what the weekend holds for our weary traveler van. I talked to my mechanic yesterday who offered to do a leak down test on the house but like I said, looks like the problem has been identified.
This team, this wonderful helpful group of strangers, has been an resource of immeasurable value! With help from my favorite Uncle (THANKS EARLE!), Chevymahr (and a few others) at the astrosafai website and Johnathan at my local dealership... we just may keep another highly capable Astro out of the wrecking yard. I might even take down the for sale sign ;-)
THANK YOU EVERYONE!
- Seafoam in crankcase certainly cleaned things up, however, as pointed out by our friend Mwilliamshs above... wrong end. I also did a round of BG's Engine Performance Restorer on fresh oil for giggles and well I think the Seafoam got the bulk of it.
- Added 32oz Seafoam to ~12 gals of gas (x3 recommended dilution) and ran 60 miles under normal load; NOTICEABLE IMPROVEMENT! Instead of barely running and shaking violently, it just shakes now. Although far from the finish line, I believe we have isolated the issue because now we can turn it off and on.
- Full Seafoam trick coming this weekend.
I was surprised to find that a $7 can of Seafoam improved my exponentially declining issue. Can't wait to see what the weekend holds for our weary traveler van. I talked to my mechanic yesterday who offered to do a leak down test on the house but like I said, looks like the problem has been identified.
This team, this wonderful helpful group of strangers, has been an resource of immeasurable value! With help from my favorite Uncle (THANKS EARLE!), Chevymahr (and a few others) at the astrosafai website and Johnathan at my local dealership... we just may keep another highly capable Astro out of the wrecking yard. I might even take down the for sale sign ;-)
THANK YOU EVERYONE!
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nobodyhome
Adventurer
Thanks CJ, if it comes down to replacing heads I will have to bail on it due to funds. The EGR is a quick fix so I will look into it as well. Appreciate your advice.